Help debugging a diy small clone

[duck0872]

Hey everyone, i'm on a roll this week.  2 builds and 2 pedals not working.  Guh.  I have a Tonepad diy small clone that is not working correctly.

The link to the project pdf is here http://www.tonepad.com/getFile.asp?id=97

I designed the board myself using eagle, but I have built several of these that worked so I know the board design is sound. I have verified all IC are in correct orientation, as are the trans and polar electrolytic caps.  All caps are of the correct value.

I made three substitutions.  I have a TL072 in place of the 4558,instead of using a tantalum cap for c15 i used a regular polar electrolytic cap, and C7 is .0022 instead of .0027.  Everything else is the same.

When i turn on the effect, there is no chorus.  The dry signal comes through fine when both on and bypassed.  voltages as follows

input voltage at the board is 9.36

IC1 TL072
1- 4.52
2- 4.53
3- 3.60
4- 0
5- 4.40
6- 4.52
7- 4.52
8- 9.08

IC2 CD4047
1- 8.40
2- .04
3- 6.96
4- 8.48
5- 8.48
6- 8.49
7- 0
8- 0
9- 0
10- 4.23
11- 4.24
12- 0
13- 8.40
14- 8.48

IC3 LM358N
1- 6.72
2- 6.86
3- 7.05
4- 7.40
5- 6.82
6- 6.75
7- 7.76
8- 9.08

IC4 MN3007
1- 8.48
2- 4.24
3- .05
4- 0
5- 0
6- 4.23
7- 8.10
8- 8.10

Q1 2N5087 - (ebc) 0  3.65  0

Q2 2N5088- (ebc) 7.63  7.36  9.08

Q3 2N5088- (ebc) 8.48  8.91  9.09


I'm guessing there's something wrong with the 0's at Q1 ?

[maartendh]

are d1 and the 12K properly connected (how much voltage?)

[vigilante397]

Looks like serious problems with all of the transistors. If you have the same voltage or close to the same voltage on all three pins, that's generally bad news.

[duck0872]

are d1 and the 12K properly connected (how much voltage?)

Well that was one of the problems, but apparently not all of them lol.  The trace connecting r8 to r9/d1 was eroded during the etch.  I have fixed that and now have 8.86 volts at d1.  The pedal is still doing the same thing, dry signal goes through fine but no effect.  new voltages as follows.

board input voltage still 9.36
Tl072 voltages are the same

IC 2 4047-
1-8.27
2-0.09
3-7.58
4-8.45
5-8.45
6-8.45
7-0
8-0
9-0
10-4.19
11-4.21
12-0
13-8.28
14-8.45

IC3 LM358-
1-6.63
2-6.99
3-6.99
4-7.31
5-6.73
6-6.67
7-7.75
8-9.07

MN3007-
1-8.45
2-4.21
3-8.09
4-0
5-0
6-4.19
7-8.06
8-8.06

q1 (ebc) 7.96  8.87  0

q2- 7.60  7.33  9.07

q3- 8.45  8.97  9.08

[Fender3D]

Q3's "e" must have the same voltage as IC4's pin 1 and IC2 pins 4, 5, 6 and 14.
Q1 is shorted to GND and Q2's emitter resistor is not connected to GND...

Eagle's ERC does not work or errors on schematic, maybe?

[duck0872]

Q3's "e" must have the same voltage as IC4's pin 1 and IC2 pins 4, 5, 6 and 14.
Q1 is shorted to GND and Q2's emitter resistor is not connected to GND...

Eagle's ERC does not work or errors on schematic, maybe?

Q2 emitter resistor has good continuity to ground.  I should note that I did not realize the numbering of q2 and 3 were reversed from what they were on my eagle schematic.  I have changed my posts so that all numbering is the same as the numbering on the tonepad project.  I apologize for this oversight.

[PRR]

> IC3 LM358-
> 1-6.63
> 2-6.99
> 3-6.99
> 4-7.31
> ....
> 8-9.07

We expect to find 9V on one pin and zero V on another pin. Else the darn chip is not getting fed.

Is pin 4 not really going to Gnd/0V as seen on the TonePad plan?

[duck0872]

> IC3 LM358-
> 1-6.63
> 2-6.99
> 3-6.99
> 4-7.31
> ....
> 8-9.07

We expect to find 9V on one pin and zero V on another pin. Else the darn chip is not getting fed.
Is pin 4 not really going to Gnd/0V as seen on the TonePad plan?

I noticed the same thing when I was hunting for solder bridges, pin 4 was not going to gnd.  I resoldered and have good cont. to gnd, but still not working.  voltages have changed so here's the updated voltages, as before 9.36 into board

tl072 is the same

IC2 4047-
1-8.26
2-.07
3-7.27
4-8.40
5-8.40
6-8.40
7-0
8-0
9-0
10-4.18
11-4.19
12-0
13-8.27
14-8.40

IC3 LM358-

1-1.75 varying to 1.77
2-4.10
3-3.79
4-0
5-2.23 varying to 2.26
6-2.11
7-4.05 varying to 4.17
8-9.01

IC4 MN3007-
1-8.39
2-4.19
3-4.03
4-0
5-0
6-4.18
7-8.01
8-8.01

q1- 3.60  2.85  0
q2- 7.65  7.29  9.03
q3- 8.40  8.92  9.03

[PRR]

Audio probe.

[duck0872]

Audio probe.

After some basic probing I could find signal only on pin 3 of the mn3007 and q1, and none on the lm358.  There is no signal on either of the pots.  All the signal is dry, no chorused signal. When I have more time later today I'll do some more in depth probing.